Acopper ore containing 4.3 wt% water, 10.3 wt% cuso, and 85.3 wt% rock is fed to a staged counter current extractor at a rate of 11.7 tons per hour. we wish to recover 98% of the copper sulfate using pure water as the fresh solvent. the solution produced is to be 10 wt% copper sulfate and 90 wt% water. if after each stage 1 ton of inert rock retains 2 tons of water plus the dissolved copper sulfate, how many stages are required?

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.